B. seems to be the right answer.
The underlined phrase is this one:
"<span>fog rolling down the river"
The correct answer is this one: "Absolute Phrase." </span><span>Absolute phrases do not directly connect to or modify any specific word in the rest of the sentence; instead, they modify the entire sentence, adding information. </span>
<span>It rained heavily during the afternoon, but we managed to have our picnic anyway.
(The last option.)
Hope this helps~!
~My taste in music is your face</span>
I found this funnier then it should have been